Commonwealth environmental water use
options 2013-14: Lachlan River Valley
1
Cover image credit: Lachlan River Valley. Photo by Stephanie Secomb © CEWO
Acknowledgement of the Traditional Owners of the Murray-Darling Basin
The Commonwealth Environmental Water Office respectfully acknowledges the Traditional
Owners, their Elders past and present, their Nations of the Murray– Darling Basin, and their
cultural, social, environmental, spiritual and economic connection to their lands and waters.
This report should be cited as ‘Commonwealth environmental water use options 2013-14: Lachlan River Valley’.
Published by the Commonwealth Environmental Water Holder for the Australian Government.
© Commonwealth of Australia 2013.
This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by
any process without prior written permission from the Commonwealth. Requests and enquiries concerning
reproduction and rights should be addressed to Department of Sustainability, Environment, Water, Populations and
Communities, Public Affairs, GPO Box 787 Canberra ACT 2601 or email [email protected]
Information presented in this document may be copied for personal use or published for education purposes, provided
that any extracts are fully acknowledged. The views and opinions expressed in this publication are those of the authors
and do not necessarily reflect those of the Australian Government or the Minister for Sustainability, Environment, Water,
Population and Communities. While reasonable efforts have been made to ensure that the contents of this publication
are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the
contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use
of, or reliance on, the contents of this publication
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Commonwealth environmental water use options
2013-14: Lachlan River Valley
Table of contents
1. Introduction ........................................................................................................ 5
2. Context for water use in 2013-14 in the Lachlan River Valley ....................... 6
2.1.
Delivering environmental water to the Lachlan River Valley ............................................ 6
2.2.
Operational and management considerations for 2013-14 in the Lachlan River Valley 8
2.3.
Valley condition ....................................................................................................................... 10
3. Water availability ............................................................................................. 11
3.1.
Commonwealth environmental water holdings in the Lachlan River Valley for 2013-14
..................................................................................................................................................... 11
3.2.
Other sources of environmental water allocations ........................................................... 11
3.3.
Natural or unregulated flows and planned environmental water................................. 11
4. Planning for water use in the Lachlan River Valley in 2013-14 .................... 13
4.1.
Planning for a range of inflows in 2013-14 ........................................................................... 13
4.2.
Implementing watering actions throughout the year ...................................................... 13
5. Water use options and the Basin Plan’s environmental watering plan
objectives ......................................................................................................... 15
5.1.
Demonstrating how Commonwealth environmental water in 2013-14 will contribute to
the Basin Plan’s environmental watering plan objectives –Lachlan River Valley ....... 15
6. Water use options for 2013-14 ........................................................................ 16
6.1.
Watering options ...................................................................................................................... 16
6.2.
Assessment of environmental watering options ................................................................ 26
7. Accounting for the use of Commonwealth environmental water .............. 27
7.1.
Water use accounting ............................................................................................................ 27
7.2.
Operational monitoring .......................................................................................................... 27
8. Partnerships ...................................................................................................... 28
9. Bibliography ..................................................................................................... 29
3
List of Figures
Figure 1: Map of the Lachlan River Valley. ................................................................................................7
Figure 2: Water resource availability and potential inflow scenarios for the Lachlan River
Catchment over the course of 2013–14 from a starting point of moderate - high resource
availability. .................................................................................................................................................... 13
List of Tables
Table 1: Operational considerations for the Lachlan River Valley in 2013–14. ...................................9
Table 2: Commonwealth environmental water holdings in the Lachlan River Valley as at 30 April
2013. ............................................................................................................................................................... 11
Table 3: Other potential sources of environmental water in the Lachlan River Valley for 2013–14
as at 30 April 2013. ....................................................................................................................................... 11
Table 4: Expected outcomes from the use of Commonwealth environmental water in the
Lachlan River Valley. ................................................................................................................................... 15
Table 5: Summary of water use options for the Lachlan River Valley in 2013-14. .......................... 17
4
1. Introduction
This document is designed to be read in conjunction with the Commonwealth environmental
water use options 2013-14: Planning approach, which outlines the approach to planning for
the use of Commonwealth environmental water this coming water year. The planning
document provides the context for key aspects of the approach including determining
resource availability, the expected outcomes from watering actions and the relationship
between the function of the Commonwealth Environmental Water Office (the Office) and the
Basin Plan.
This document outlines watering options for the use of Commonwealth environmental water in
the Lachlan River Valley this year. The options, which describe potential watering actions, series
of actions, or watering strategies, do not represent a commitment for water use. Consistent
with the Office’s framework, decisions to make water available for any of the potential options
will be subject to an assessment against five published criteria (available from the Office’s
website) and seasonal, operational and management considerations at the time of the
action. All relevant watering actions will be assessed to ensure the best possible use of
environmental water within the relevant planning area and across the Murray-Darling Basin
and having regard to the Murray-Darling Basin Authority’s Basin annual environmental watering
priorities, once published.
5
2. Context for water use in 2013-14 in the
Lachlan River Valley
2.1.
Delivering environmental water to the Lachlan River Valley
Flows in the Lachlan River Valley are driven by rainfall in the upper catchment which are
regulated by Wyangala Dam and three main tributary river systems; the Boorowa, Belubula
and Mandagery rivers. Delivering water in the Lachlan River Valley is complex as it is a very
long system with many meandering anabranches and distributary creeks that terminate in
wetlands. Flow attenuation in the system is high due to the low gradient of the system and it
can take 90 days for a flow event from Wyangala Dam to reach the end of the river system at
Great Cumbung Swamp (BWR 2011). This creates a challenge for water managers when trying
to deliver environmental water.
Water supplies are regulated by Wyangala Dam (1220 GL), Lake Cargelligo (36 GL) and Lake
Brewster (154 GL) (MDBA 2012b). Lake Cargelligo and Brewster are lower in the valley than
Wyangala and can reduce the travel times for water delivery to the lower reaches of the
Lachlan River Valley, making delivery more efficient.
Environmental water delivery within the valley occurs in two main ways. During in-channel river
flows, Commonwealth environmental water is gravity-fed or regulated using infrastructure into
anabranches, creeks and wetlands. During high river flows water passes overbank into
floodplain and wetland sites. Where possible, environmental water will be managed to benefit
multiple sites en route to maximise the efficiency and effectiveness of water delivery.
The Water Sharing Plan for the Lachlan Regulated River Water Source (2004) provides for
planned environmental water and stock and domestic (replenishment flows) releases. These
releases offer opportunities to “piggy back” Commonwealth environmental water onto these
river flows and increase the potential for environmental objectives to be achieved and assist
with delivery efficiency.
Figure 1 below shows a map of the Lachlan River Valley.
6
Figure 1: Map of the Lachlan River Valley.
7
2.2.
Operational and management considerations for 2013-14 in the
Lachlan River Valley
The delivery of environmental water in the Lachlan River Valley is currently constrained by the
release capacities from storages, channel capacities, low lying floodplain areas and
distributary systems. Watering options will be developed in consideration of the following
constraints:
o
Lake Brewster release capacity – a maximum of 3,000 ML/day.
o
Willandra Weir – flows above 2,400 ML/day in the Lachlan River upstream of Willandra
Weir commence flows in Willandra Creek.
o
Risks to private infrastructure – delivering flows exceeding approximately 2,800 ML/day at
Hillston could require some private irrigation pumping infrastructure to be temporarily
relocated to avoid inundation.
Operational considerations such as delivery methods, opportunities, constraints and risks will
differ depending on the inflow scenario and are summarised in Table 1. Operational
considerations are assessed against inflow scenarios which are represented by annual
exceedance probability (AEP), that is, the number of years that a given inflow volume is
equalled or exceeded, expressed as a percentage.
Environmental water may be made available for some watering options from NSW Office of
Environment and Heritage (NSW OEH) either as adaptive environmental water or discretionary
planned environmental water. This environmental water may be used to complement the use
of Commonwealth environmental water.
Throughout the year seasonal, operational and management considerations will be addressed
as decisions are taken to make water available for use and as these decisions are
implemented. This will include refining the ecological objectives, assessing operational
feasibility and potential risks and the ongoing monitoring of the seasonal outlook and river
conditions.
8
Table 1: Operational considerations for the Lachlan River Valley in 2013–14.
Inflow scenario
Very low
(90%
AEP1)
Low
(75%
AEP)
Moderate
(50%
AEP)
High
(25%
AEP)
Very high
(10%
AEP)
Opportunities
Manage the recession of naturally
occurring high flows to provide for a more
natural flow pattern.
Use environmental water in conjunction
with, or to maximise the environmental
benefit of, naturally occurring river flows.
Use environmental water to support bird
breeding events and aquatic species
propagation/breeding requirements
Constraints
Natural flows meet environmental flow
requirements, reducing the need for and
effectiveness of the release of
environmental water.
Delivery options are limited due to high
unregulated flows resulting in reduced
channel capacity, limiting the operation of
river infrastructure and inhibiting additional
releases from storages.
Flow thresholds for existing river
infrastructure may constrain the delivery of
environmental water.
Risks*
The provision of Commonwealth
environmental water must consider
potential inundation impacts to property
and infrastructure.
Percentages refer to the probability of exceedance based on historical inflows for the valley,
i.e. there is a 90 per cent chance that actual flows will be greater than that amount.
1
9
Inflow scenario
Very low
(90%
AEP1)
Low
(75%
AEP)
Moderate
(50%
AEP)
High
(25%
AEP)
Very high
(10%
AEP)
Potential impacts on private infrastructure
requiring relocation of pumps etc
* See Section 6.2 for more information on risk management.
2.3.
Valley condition
Between 2000 and 2010 the Lachlan River Valley received low inflows due to a long period of
drought, which, coupled with river regulation, had a significant effect on the environmental
condition of the valley. The Murray–Darling Basin Authority released its second Sustainable
Rivers Audit report in 2012 (based on data collected from 2008 to 2010) and concluded that
the Lachlan River Valley was in very poor river ecosystem health. While the Lachlan River Valley
was recognised as having good physical form and moderate macroinvertebrate communities
and hydrology, the valley was rated as poor for riparian vegetation and very poor for native
fish communities (MBDA 2012b).
Some moderate inflows occurred during this period in 2001-02 and 2005-06, but droughtbreaking inflows were experienced in 2010–11 with further high inflows experienced across the
valley in 2011–12, particularly during the second half of the year. These flows inundated large
areas of floodplain wetland with some areas for the first time in a decade (LRWG 2013). Areas
such as Lake Bullogal, Ryan’s Lake and Lake Ita in the lower part of the system received inflows
for the first time since 1990 (BWR 2011).
Most areas within the Lachlan River Valley are in various stages of recovery. This recovery is
evidenced by large bird breeding events at key locations such as Booligal Wetlands, Merrowie
Creek and Lake Brewster (NSW OEH 2012a). Further evidence is the regeneration of river red
gums and vigorous growth of lignum and reed beds across the Lachlan system, especially at
Murrumbugil Swamp and Lake Ita (NSW OEH 2012b). In addition, threatened species previously
thought extinct in the area, such as the Southern Bell Frog has been recorded in the area
following three years of high flows (Paul Packard, pers. comm. 11/09/2012).
The 2012–13 water year saw a return to drier than average conditions in the Lachlan River
Valley. Rainfall was below average to very much below average across the entire valley.
Water storage across the valley remains high; the main storage Wyangala Dam is at 75 per
cent. However inflows into Wyangala to date have been low and translucent dam releases
are unlikely. Threatened species and vegetation regeneration will require support in the
coming water years to ensure their survival and to continue to improve their condition.
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3. Water availability
3.1.
Commonwealth environmental water holdings in the Lachlan River
Valley for 2013-14
Commonwealth environmental water holdings available for use in 2013–14 in the Lachlan River
Valley are shown in Table 2 below.
Table 2: Commonwealth environmental water holdings in the Lachlan River Valley as at 30 April
2013.
Entitlement type
Entitlement held
(GL)
Long-term
average annual
yield (GL)
Expected
carryover
from
2012–13 (GL)1
Forecast
water
availability
for
2013–14 (GL)2
Lachlan(high
security)
0.7
0.7
0
Lachlan (general
security)
Total
86.9
36.5
40-70
44-124
(Up to 87.7
available within
use limits.)
87.7
37.2
40
Notes:
1. Future decisions about use, transfers and the ability to deliver already approved actions will
affect expected carryover from 2012-13.
2. Forecasts are based on the best available information including State forecasts and
historical inflow scenarios. Forecasts include carryover from 2012-13. Forecasts for are given
to the nearest whole gigalitre.
The full list of Commonwealth environmental water holdings can be found at the Office’s
website and is updated monthly. A portfolio management statement for the Lachlan River
Valley is available here.
3.2.
Other sources of environmental water allocations
Other sources of environmental water that may be used to complement Commonwealth
environmental water delivery in the Lachlan River Valley include water held by NSW OEH. Table
3 below outlines the different environmental water entitlements held by other water holders.
Table 3: Other potential sources of environmental water in the Lachlan River Valley for 2013–14
as at 30 April 2013.
Source
NSW Environmental Water
Holdings
3.3.
Management Authority
Entitlement
NSW OEH
25,752 ML
Natural or unregulated flows and planned environmental water
In addition to water entitlements held by environmental water holders, environmental
demands may also be met via natural or unregulated flows and water provided for the
environment under rules in state water plans (referred to as ‘planned environmental water’).
In the Lachlan River Valley, there are two ecological contingency allowances and a water
quality allowance provided for under the Lachlan Water Sharing Plan which are managed by
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NSW agencies. Translucent releases from Wyangala Dam are also provided for under the
Lachlan water sharing plan and are managed by NSW State Water Corporation. For more
information on the operation of water sharing plan planned environmental water please refer
to the NSW Office of Water website. The Bureau of Meteorology provides a seasonal
streamflow forecasting service, which estimates the potential for low, median or high flows for
the coming three months ahead.
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4. Planning for water use in the Lachlan River
Valley in 2013-14
4.1.
Planning for a range of inflows in 2013-14
In addition to influencing opportunities, constraints and risks in relation to environmental
watering (see Table 1), inflows are a primary driver of resource availability. Resource availability
also reflects a combination of the allocations available to the Commonwealth Environmental
Water Holder (Section 3.1 above) and other environmental water holders (Section 3.2) as well
as natural or unregulated flows and planned environmental water (Section 3.3).
Given the variable rainfall experienced across the Basin, inflows are difficult to accurately
forecast. As shown in Table 2, carryover from 2012–13 for the Lachlan is likely to be in the range
of approximately 40-70 GL. Future decisions about use, transfers and the ability to deliver
already approved actions will affect this. Forecast early season allocations (up to 31 July 2014)
are likely to be low.
Consideration of this allocation range relative to the total entitlement volume (Table 2) and the
full range of inflows that may be possible suggests that resource availability early in 2013–14
may be moderate to high. From this starting point, the full range of possible inflows suggest that
resource availability over the course of the year could be between low and very high, and
unlikely to become very low (Figure 2). As such, the water use options described in
Section 6 have been developed for a range of resource availability between low and very
high.
Figure 2: Water resource availability and potential inflow scenarios for the Lachlan River
Catchment over the course of 2013–14 from a starting point of moderate - high resource
availability.
4.2.
Implementing watering actions throughout the year
Resource availability will change over the course of 2013–14 as new allocation
announcements are made and water is used or traded. Climatic conditions will also affect the
potential for inflows. The Office will regularly review allocations against environmental
entitlements and seasonal streamflow forecasts over the course of the year to assess resource
13
availability. This assessment, along with up-to-date information on environmental needs and
the operational and management conditions (Section 2) will allow the watering options in
Section 6 to be refined for implementation as required.
14
5. Water use options and the Basin Plan’s
environmental watering plan objectives
5.1.
Demonstrating how Commonwealth environmental water in 2013-14 will
contribute to the Basin Plan’s environmental watering plan objectives –
Lachlan River Valley
Commonwealth environmental water use options for the Lachlan River Valley in 2013–14
include the following four flow types:
 base flows

freshes

bankfull

overbank.
Wetlands and floodplains are also expected to be inundated. The flows types are illustrated in
Figure 3 of the document Commonwealth environmental water use options 2013-14: Planning
approach.
The ecological response from delivering Commonwealth environmental water is reflected in
the expected outcomes.
The Commonwealth Environmental Water Office (the Office) has used the best available
science to determine how the expected outcomes of Commonwealth environmental water
contribute towards the objectives of the Basin Plan’s environmental watering plan.
Table 4 shows the expected outcomes that may be derived from Commonwealth
environmental watering using different flow types in the Lachlan River Valley and the relevant
Basin Plan objectives.
Table 4: Expected outcomes from the use of Commonwealth environmental water in the
Lachlan River Valley.
Flow Type
Expected outcomes
for 2013–14
Contributions to longer
term outcomes
Contribution to the following
Basin Plan objective
Base flows
Refuges
Recovery
Resilience
Dissolved oxygen
Chemical
Water quality
Fish reproduction
Landscape fish diversity
Biodiversity
Waterbird
reproduction
Landscape bird
diversity
Base flows and
freshes
Waterbird fledging
Hydrological
connectivity
Connectivity
Ecosystem function
Biotic dispersal
Freshes, bankfull
and overbank
Vegetation condition
and reproduction
Landscape vegetation
diversity
Biodiversity
Overbank
End of system flows
Connectivity
Ecosystem function
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6. Water use options for 2013-14
6.1.
Watering options
Potential watering options for 2013–14 have been developed for the Lachlan River Valley.
These reflect the approach to supply Commonwealth environmental water to contribute to
the overall environmental objectives under the Basin Plan’s environmental watering plan.
These watering options have been designed to specifically enable the scaling of actions
across several potential inflow scenarios. This provides flexibility for water use to best
complement natural inflows. Options have not been developed for a very high inflow scenario
(and the relevant resource availability) in recognition that at these times, large areas of the
Lachlan River Valley would likely be experiencing flooding. Such flooding would achieve many
environmental outcomes and provision of additional environmental water would likely cause
adverse third party impacts.
Broadly, the aim of Commonwealth environmental watering in the Lachlan River Valley during
2013–14 will be to support the on-going environmental recovery that commenced following
the breaking of the drought (see Section 2.3). For some parts of the system, this will mean
providing river flows to support vegetation health in wetlands, the riparian zone and on
floodplains. For other parts of the system, this may mean making decisions not to provide water
to sites that require a drying phase.
Any volumes described in the options tables below are approximations only. The final volume
of Commonwealth environmental water made available will depend on river conditions at the
time of use, other environmental water contributions and in consideration of Basin-wide needs.
The water use options identified do not represent a commitment for use, nor do they reflect all
the possible water use options available. Additional water use options may be identified
throughout the water year. The Office welcomes information from the community on how
environmental water can best be used and managed. If you have any comments or
suggestions, please call 1800 218 478 or send an email to: [email protected]
16
Table 5: Summary of water use options for the Lachlan River Valley in 2013-14.
Applicable level(s) of
resource availability
(see Section 4)
Low
Moderate
High
Very High
Option 1 - Lachlan Swamps,
Lake Ita and Great
Cumbung Swamp
Contribute to overbank flows during autumn-winter to improve vegetation condition, contribute
to recruitment and provide ideal conditions for further growth during the following spring and
summer.
Option unlikely to be pursued
under this resource availability.
Option 2 - Lachlan River
between Jemalong and
Lake Cargelligo
Contribute to fresh flows during spring to provide hydrological connectivity allowing fish
movement and access to breeding habitat at key breeding times
Option unlikely to be pursued
under this resource availability.
Option 3 - Lachlan River
downstream of Lake
Brewster
Option 4 - Muggabah
Creek (Lower Gum)
Contribute to base flows to
refresh drought refuges and
reduce the risk of water
quality conditions degrading
Option unlikely to be pursued under this resource availability.
Contribute to bankfull flows between Aug-Sept to support
vegetation recruitment and extent
Option unlikely to be pursued under this resource availability.
Option 5 - Merrimajeel
Creek
Contribute to bankfull flows between July-Sept to support
vegetation recruitment and extent
Option unlikely to be pursued under this resource availability.
Option 6 - Merrowie Creek
Contribute to bankfull flows between July-Sept to support
vegetation recruitment and extent
Option unlikely to be pursued under this resource availability.
Option 7 - Water Bird
Reproduction and Fledging
Contingency
Option unlikely to be pursued
under this resource availability.
Contribute to fresh flows to support waterbird reproduction and
fledging if required
Option unlikely to be pursued
under this resource availability.
Note: Under certain resource availabilities, options may not be pursued for a variety of reasons including that environmental demand may be met by
unregulated flows, constraints and/or risks may limit the ability to deliver environmental water etc.
17
Option 1 – Lachlan Swamps, Lake Ita and Great Cumbung Swamp
Catchment: Lachlan
Complex: Lachlan Swamps and Great Cumbung Swamp
Site: Lake Waljeers, Peppermint Swamp, Lake Ita and Great Cumbung Swamp
Applicable level(s) of resource availability: Moderate - High
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows/Terminal Wetland
Summary of watering option:

The purpose this option is to provide flows into the floodplain and wetland areas of the
Lachlan Swamps to consolidate the benefits of natural inundation provided during 2011–12
and early 2012–13. Many areas in the Lachlan Swamps including Lake Ita received inflows
from the 2011–12 flood event for the first time at least 10 years and vegetation response has
been strong.

Inundation in late 2012–13 and early 2013–14 will improve vegetation condition and
contribute to recruitment by providing soil moisture to seedlings and regenerating
vegetation which should provide ideal conditions for further growth during the following
spring and summer.

To achieve this outcome, Commonwealth environmental water will contribute to flows of
1,200 ML/day for at least 40 days at Booligal Weir between May-August. Commonwealth
environmental water would be delivered from Lake Brewster.
Timing
May 2013 to August 2013
Volume of
Commonwealth
environmental water
Up to 70 GL
Operational considerations and feasibility:

This option will be coordinated with NSW OEH to ensure complementary delivery. NSW OEH
manage held and planned environmental water for NSW (including the ecological
contingency allowances).

Effective delivery of this option is contingent on the following arrangements being in place:
o
Water management by State Water Corporation is such that the water order can be
delivered to the lower reaches of the river, that is, adequate volumes in Lake
Brewster or in the river system to meet the order. Additional water may need to be
transferred from Wyangala Dam to meet the volume of this order.
o
Minimisation flows to non target areas (e.g. Willandra, Muggabah, Merrimajeel
&Torrigany Creek) through the use of water management infrastructure.
o
Accounting points and arrangements for losses to non target areas (e.g. Willandra
18
Creek) agreed with State Water Corporation.

Achieving a target of up to 1,200 ML/day at Booligal will create conditions in the river such
that some inflow into Lake Ita may occur. Being a terminal system, this option will provide
inflows into the Great Cumbung Swamp (approximately 300-400 ML/day).
19
Option 2 – Lachlan River between Jemalong and Lake Cargelligo
Catchment: Lachlan
Complex: Lachlan River
Site: Lachlan River between Forbes and Lake Cargelligo
Applicable level(s) of resource availability: Low to High
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows/Terminal Wetland
Summary of watering option:

The purpose this option is to provide flows to drown out weirs in the Lachlan River near
Condobolin NSW. This option will provide hydrological connectivity allowing fish movement
and access to breeding habitat at key breeding times. These flows would provide more than
200 km of unimpeded fish passage.

This watering option would contribute to fish outcomes by supporting threatened fish
communities, fish reproduction and fish diversity especially large bodied native fish including
Murray Cod which are known to require a minimum of 14 days access to breeding habitat to
lay eggs, hatch and disperse.

To achieve this outcome, Commonwealth environmental water will contribute to flows of up
to 4,100 ML/day at Condobolin for approximately 14 days between September and
November when river temperature are above 15 degrees Celsius. Commonwealth
environmental water will be delivered from Wyangala Dam to the target area.
Timing
Spring
Volume of
Commonwealth
environmental water
Up to 50 GL
Operational considerations and feasibility:

This option will be coordinated with NSW OEH to ensure complementary delivery. NSW OEH
manage held and planned environmental water for NSW (including the ecological
contingency allowances).

The Lachlan Water Sharing Plan limits regulated releases in this reach of the river to 2,600
ML/day. Negotiation with State Water Corporation will need to occur in order for a higher
volume to be delivered.

Opportunities to piggyback on a natural event or regulated flow (irrigation supply or bulk
water transfers to Lake Brewster) will be sought. Coordination with State Water Corporation
and the management of water resources in the Lachlan River Valley would be required to
ensure the most efficient outcome.

Some flows not required to meet immediate irrigation orders maybe be able to be regulated
in Lake Brewster downstream.
20
Option 3 - Lachlan River downstream of Lake Brewster
Catchment: Lachlan
Complex: Lachlan River
Site: Lachlan River downstream of Lake Brewster
Applicable level(s) of resource availability: Low
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows/Terminal Wetland
Summary of watering option:

The purpose of this option is to provide flows to provide hydrological connectivity to refresh
drought refuges in the lower reaches of the Lachlan River. This option maintains essential
refuge habitat for aquatic species during periods of low to no flow.

During periods of low or no flow, environmental flows may be required to ensure the
persistence of pools in stream as refuge and reduce the risk of water quality conditions
degrading, particularly low dissolved oxygen levels. This option would occur after a
protracted period of low or no flows.

To achieve this outcome, Commonwealth environmental water will contribute to flows
between 50-100 ML/day at Booligal as required. Commonwealth environmental water
would be delivered from Lake Brewster and managed within the normal water delivery
arrangements.
Timing
Any time
Volume of
Commonwealth
environmental water
5-10 GL
Operational considerations and feasibility:

This option will be coordinated with NSW OEH to ensure complementary delivery. NSW OEH
manage held and planned environmental water for NSW (including the ecological
contingency allowances).
21
Option 4 - Muggabah Creek and Associated Wetlands
Catchment: Lachlan
Complex: Booligal Wetands
Site: Muggabah Creek and associated wetlands
Applicable level(s) of resource availability: Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The purpose of this option is to provide flows into the Muggabah Creek system, targeting
riparian areas and Lower Gum Swamp to consolidate the benefits of natural inundation
provided during 2011–12 and 2012–13.

River red gum stands in Lower Gum Swamp are in poor condition with more than 75 per
cent of trees being assessed as dead in 2011–12. Lachlan Water Sharing Plan
replenishment flows do not inundate the Swamp. However, the high flows experienced
from the 2011–12 event inundated the area and there are reports of some regeneration of
vegetation communities. Additional inflows to support vegetation recruitment and extent
will be required.

To achieve this outcome, Commonwealth environmental water will contribute to flows of
up to 100 ML/day for between 30-40 days depending on antecedent conditions and other
flows in the system. Commonwealth environmental water would be delivered from Lake
Brewster to Torriganny creek and directed into Muggabah Creek through a regulator.
Timing
July - September
Volume of
Commonwealth
environmental water
Up to 5 GL
Operational considerations and feasibility:

This option will be coordinated with NSW OEH to ensure complementary delivery. NSW OEH
manage held and planned environmental water for NSW (including the ecological
contingency allowances).

Opportunities to piggyback this option on a Water Sharing Plan replenishment flow or
natural event will be sought.

This option may not be required if other flows are deemed sufficient to support vegetation
recruitment and extent.
22
Option 5 - Merrimajeel Creek and Associated Wetlands
Catchment: Lachlan
Complex: Booligal Wetands
Site: Merrimajeel Creek and associated wetlands
Applicable level(s) of resource availability: Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The purpose of the option is to provide flows into the Merrimajeel Creek system, targeting
riparian areas and wetlands such Murrumbigil Swamp and Lake Merrimajeel to consolidate
the benefits of natural inundation provided during 2011–12 and 2012–13.

To achieve this outcome, Commonwealth environmental water will contribute to flows of
up to at 100 ML/day for between 30-70 days depending on antecedent conditions and
other flows in the system. Flows will then be gravity fed to the target site. Commonwealth
environmental water would be delivered from Lake Brewster to Torriganny Creek and
directed into Merrimajeel Creek through a regulator.
Timing
July - September
Volume of
Commonwealth
environmental water
Up to 7 GL
Operational considerations and feasibility:

This option will be coordinated with NSW OEH to ensure complementary delivery. NSW OEH
manage held and planned environmental water for NSW (including the ecological
contingency allowances).

Opportunities to piggyback this option on a Water Sharing Plan replenishment flow or
natural event will be sought.

This option may not be required if other flows e.g. water sharing plan replenishment flows
are deemed to support vegetation recruitment and extent.
23
Option 6 – Merrowie Creek and Associated Wetlands
Catchment: Lachlan
Complex: Merrowie Creek and associated wetlands
Site: Merrowie Creek
Applicable level(s) of resource availability: Low to Moderate
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows
Summary of watering option:

The purpose of the option is to provide flows into the Merrowie Creek system, targeting
wetlands such as Cuba Dam and Lake Tarwong to consolidate the benefits of natural
inundation provided during 2011–12 and 2012–13.

To achieve this outcome, Commonwealth environmental water will contribute to flows of
between 150-200 ML/day for approximately 90 days. Commonwealth environmental water
would be delivered from Lake Brewster to Merrowie off-take regulator.
Timing
July - September
Volume of
Commonwealth
environmental water
20 GL
Operational considerations and feasibility:

This option will be coordinated with NSW OEH to ensure complementary delivery. NSW OEH
manage held and planned environmental water for NSW (including the ecological
contingency allowances).

Opportunities to piggyback this option on a Water Sharing Plan replenishment flow or
natural event will be sought.

This option may not be required if other flows e.g. water sharing plan replenishment flows
are deemed sufficient to support emergent vegetation.
24
Option 7 – Water Bird Reproduction and Fledging Contingency
Catchment: Lachlan
Complex: TBA as required
Site: TBA as required
Applicable level(s) of resource availability: Moderate to High
Relevant flow component:
Expected inundation extent:
Base flows
Floodplain inundation
Fresh
Wetland inundation
Bank-full flows
Over-bank flows/Terminal Wetland
Summary of watering option:

The wetlands in the Lower Lachlan system are known to support colonial waterbird
reproduction events in areas such as Booligal Wetlands and Cuba Dam. The purpose of this
option is to support colonial waterbird reproduction events for species such as glossy ibis and
white ibis.

If a waterbird reproduction event commences but system inflows are lower than expected
and water levels in the area begin to drop, additional environmental water may be required
in order to ensure that conditions persist to support fledging of chicks. In these
circumstances, if additional environmental water would be provided to reduce the risk that
adult birds would abandon nests and the waterbird reproduction event would be
unsuccessful.

Areas likely to require water to support colonial waterbird reproduction events are the
Booligal Wetlands and Merrowie Creek (Cuba Dam). The location for this option will become
apparent once/if breeding commences. The volume and delivery pattern will be highly
dependent on the location of the waterbird reproduction event and the degree to which it
requires support from environmental water.
Timing
As required
Volume of
Commonwealth
environmental water
Up to 20 GL
Operational considerations and feasibility:

Environmental water is expected to be delivered from Lake Brewster to the target area in the
Lower Lachlan system. Flows will then be gravity fed to the target site.

This option may not be required if other flows e.g. unregulated flows or water sharing plan
replenishment flows are deemed sufficient to support the breeding to completion.
25
6.2.
Assessment of environmental watering options
The proposed watering options will be assessed closer to the proposed timing for delivery using
the criteria for assessing environmental watering actions. This assessment will form part of the
Office’s assessment of seasonal, operational and management considerations and will inform
a recommendation to the Commonwealth Environmental Water Holder to approve water use.
A description of these criteria is provided in the Framework for Determining Commonwealth
Environmental Water Use which is available here.
This assessment will include a comprehensive risk assessment which is subject to the prevailing
valley and river flow conditions, and will consider proposed costs, delivery, monitoring and
accounting arrangements, and potential third party impacts. Any additional watering options
identified during the course of the year will also be subject to an assessment against the
criteria.
26
7. Accounting for the use of Commonwealth
environmental water
7.1.
Water use accounting
Across New South Wales Commonwealth environment water is generally transferred to the
NSW OEH. NSW OEH is then responsible for making arrangements to deliver the environment
water with river operators such as State Water Corporation. In some instances, water may be
delivered without trade to NSW OEH environmental accounts.
River flows will be accounted for at storages or at downstream flow gauges and will be
reported to the Office by NSW OEH. Where applicable, water delivered to individual wetland
sites will be accounted at flow gauges or metered pumps at those sites.
7.2.
Operational monitoring
Operational monitoring is monitoring that helps assess whether water has been delivered as
planned [e.g. the volumes, timing (frequency and duration), and location and flow rates of
water delivered] and can include observations of immediate environmental responses.
This monitoring is mostly undertaken by delivery partners in conjunction with the Office. In the
Lachlan River Valley, this includes the NSW OEH, NSW State Water Corporation, and NSW Office
of Water.
Delivery partners provide regular operational monitoring updates to the Office. The operational
monitoring requirements are set out in the Office’s Operational Monitoring template.
Key parameters required through operational monitoring are:

Date of Commonwealth environmental water delivery (commencement and finish).

Point of debit/delivery (both if they are different).

Volume of Commonwealth environmental water delivered (provided on a weekly basis).

Flow rate that water is delivered at (hydrograph of delivery if possible).

Monitoring associated with identified risks.
27
8. Partnerships
The Office has consulted with a range of stakeholders to develop the Commonwealth
environmental water use options for the Lachlan River Valley for 2013–14. These include:

Environmental Water Scientific Advisory Panel

Murray-Darling Basin Authority

NSW OEH

NSW Office of Water

NSW Department of Primary Industries

Lachlan Riverine Working Group

Lachlan Catchment Management Authority.
The Office will continue to work with stakeholders and other interested community members in
the planning, delivery, management and monitoring of Commonwealth environmental water.
28
9. Bibliography
Barma Water Resource Consulting (BWR) (2011) Environmental Water Delivery – Lachlan River.
Department of Sustainability, Environment, Water Populations and Communities, Canberra.
Hamilton, S. K., Bunn, S. E., Thoms, M. C. and Marshall, J. C. (2005). Persistence of aquatic
refugia between flow pulses in a dryland river system (Cooper Creek, Australia). Limnology and
Oceanography 50, 743-754.
Lachlan Riverine Working Group (LRWG) (2013) Lachlan Environmental Water Management
Plan http://www.lrwg.com.au/ <accessed 08/03/2013>.
MDBA (2012a) Assessment of environmental water requirements for the proposed Basin Plan:
Booligal Wetlands. Licensed from the Murray-Darling Basin Authority, under a Creative
Commons Attribution 3.0 Australia Licence. MDBA Publication No: 37/12.
MBDA (2012b). Sustainable Rivers Audit 2: The ecological health of rivers in the Murray–Darling
Basin at the end of the Millennium Drought (2008–2010). Summary. MDBA Publication 75/12.
Murray-Darling Basin Authority, Canberra.
NSW DPI (2006) Reducing Impacts of Weirs on Aquatic Habitat – New South Wales detailed
weir review. Lachlan CMA region. Report to the New South Wales Environmental Trust. NSW
Department of Primary Industries, Flemington, NSW.
NSW Office of Environment and Heritage (2012a) - Environmental Water Use in NSW – Annual
Report. Office of Environment and Heritage, Sydney.
NSW Office of Environment and Heritage (2012b) Annual Environmental Watering Plan 2012–13
- Lachlan Valley, NSW Office of Environment and Heritage, Sydney NSW.
Price, A. (2009). Distrubtuion and Recruitment Patterns of Fish in the Lower Lachlan River. Final
report prepared for the Lachlan Catchment Management Authority by the Murray-Darling
Freshwater Research Centre, MDFRC Publication 17/2010.
Wallace, T and J Bindokas (2011) The impact of drought on water quality and fish communities
within refuge pools in the Lachlan River, Final Report prepared for the Lachlan Catchment
Management Authority by the Murray Darling Freshwater Research Centre MDFRC Publication
20/2011.
29